Hoisting-engine.



S. T. NELSON. HOISTING ENGINE. APPLICATION FILED SEPT. a, 1908. RENEWED FEB. 16, 1912.

* LllwflMm Patented Feb. 16,1915.

HE NORRIS PETERS co. FHQIQ-LITHr; WASHINGTON. D C,

S. T. NELSON.

HOISTING ENGINE. APPLICATION FILED SEPT. 3 ,044.

,1908. RENEWED FEB.16, 1912.

Patented Feb. 16, 1915 g SHEETSSHEET 2 Jmbw W i ww 'HE NORRIS PETERS C0.. FHOTO'LITHQ. WASHINGTON, D. C.

S. T. NELSON.

HOISTING ENGINE.

RENEWED FEB.16, 1912.

APPLICATION FILED SEPT. 3, 1908. 1,1 529,,U44. Patented Feb. 16, 1915.

THE NORRIS 'PzrsksjmuM-lnlimuwa. wAsl-uucmn. 1:. cv

SVEN '1. NELSON, OF CHICAGO, ILLINOIS.

I-IOISTiNG-ENGINE.

Specification of Letters Patent.

Patented Feb. 16, 1915.

Application filed September 3, 1908, Serial No. 451,506. Renewed February 16, 1912. Serial No. 677,959.

To all whom it may concern Be it known that I, Svnn T. Nelson, a citizen of the United b'tates, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Controlling Devices for Hoisting-Engines, of which the following is a specification.

The invention relates to hoisting engines, such as are employed for operating the cages or skips in the shafts of mines, and more particularly to safety mechanism for automatically cutting off or throttling the supply of motor fluid to the engine before the cages reach the ends of their movement in the mine shaft. Such devices are set forth in my prior Patent No. 826,956, dated July 24, 1906, and the present invention seeks to improve, simplify and cheapen the cost of manufacture of such automatic throttling mechanism and consists in the features of improvement hereinafter set forth and more particularly pointed out in the appended claims. 3

In the drawings, which illustrate the preferred form of invention, Figure 1 is a plan view of a hoisting engine with the present improvement applied thereto. Fig. 2 is a view in longitudinal section on the line 2-2 of Fig. 1. Fig. 3 is a longitudinal sec tion taken on the line 3-3 of Fig. 1 with the parts shown on an enlarged scale. Fig. 4 is a view in elevation of the controlling mechanism for the throttling means with parts shown in section on the line 44 of Fig. 3.

The hoisting engine illustrated is of the single drum type for operating two cages in the mine shaft. The cages are connected to cables wound in opposite directions upon the engine drum so that they are hoisted in balance, that is to say, one cage is raised while the other is lowered.

The drum 10, in the form shown, is mounted upon and is fixed to the engine shaft 11 and two engines are provided, one coupled to each end of the shaft 11. Each end of this shaft is journaled in a suitable bearing 12 at the forward end of the adjacent engine frame 13 and the shaft is provided at each end with a crank 14 which is engaged by the connecting rod 15 of the adjacent engine. The engine cylinder 16 in the form shown, is provided with the ordinary Corliss valve gear driven from a wrist plate 17 The latter is operated from a valve shaft 18 that extends from side to side in front of the drum 10 and is provided at either end with a crank-arm 19. .Each crank-arm 19 operates a rocker-arm 20 through the medium of a connecting link 21 and the rocker-arm in turn is connected to the wrist plate 17 by a link 22 to operate the same. The valve shaft 18 is driven from the engine'shaft through the medium of an idler gear 23 which meshes with a gear (not shown) on the engine shaft and with a gear 24 on the valve shaft. The gear 24'is loose on the valve shaft 18 and a steam cylinder 25 is connected thereto. This steam cylinder is provided with a wing piston 26, that is indicated by dotted lines in Fig. 3, and which is fixed to the shaft 18 and arranged to be engaged by one or the other of a pair of abutments 27 to rotate the valve shaft in one or the other direction in accordance with the direction of movement of the engine. Suitable steam ports and passages are provided for admitting steam on opposite sides of the wing piston 26 to shift the same and the valve shaft 18 relatively to the drive gear 24 to effect the reversal of the engine. These steam ports are controlled by a valve arranged within a valve casing 28, (see Fig. 3). The stem 29 ofthe valve is connected by a link 30 to a crank-arm 31 on one end of a short shaft 32. A crank-arm 33 on the other endof the shaft 32 is connected by a link 34 to a crankarm 35 on one end of a rock shaft 36. This rock-shaft is journaled in suitable bearings 37 mounted upon the foundation of the engine and is provided with an upwardly-projecting arm 38 that is connected by a link 39 to a hand-lever 40. By shifting the handlever 40 the engineer can move the valve of the auxiliary, reversing engine to shift the valve-shaft 18 relatively to its drive gear 24 and thus effect the reversal of the hoisting engine. This reverse gear is fully set forth in the prior Patent No. 826,956 referred to above, and need not be more fully set forth here. Any other suitable form of reverse gear may be employed without departure from the essentials of the invention.

Each of the engine cylinders is provided with a throttle valve 41, the stem 42 of which is connected to a sliding block 43. This sliding block is connected to the toggle links 44 which in turn are pivoted to the ends of toggle links 45. The latter links are pivoted at their opposite ends to the valve casing. The connected ends of the.

toggle links 44 and 45 are connected by links 46 to a crank-arm 47 that is fixed to the end of a shaft 48. This shaft extends across from one engine cylinder to the other, is journaled in suitable brackets 48 mounted on the engine cylinders, and is connected in the same manner to both throttle valves. Intermediate its ends the shaft 47 is provided with a crank-arm 49 which is connected by a link 50 to a crank-arm 51 on a short shaft 52. This shaft is journaled in suitable brackets 53 upon the foundation of the engine and is provided with an up- Wardly-projecting crank-arm 54 that is connected by a link 55 to a handlever 56. By shifting the hand-lever 56, the engineer may open and close the throttle valves. Any other suitablethrottle valves and controlling mechanism therefor could be employed. The automatic mechanism for closing the throttles is mounted upon the foundation of the engine in front of the drum 10. As stated, two cars or cages are operated by the drum, one of which moves up as the other is lowered, and means are provided for throttling the engine when either car approaches the surface. For this purpose two controlling shifters are provided, one for closing the throttles when the engine is driven in one direction and one of the cars is approaching the surface, and the other when the engine is driven in the opposite direc- "tion and the other car is approaching the surface. These shifters are controlled by actuating mechanism driven from the engine that are in the formof rotating actuator cams 57 and 57*. These cams are fixed to a shaft 58 on opposite sides of a supporting standard 59 which rises from the foundation, and in which one end of the shaft 58 is journaled. The shaft 58 extends outwardly toward one end of the drum and at its outer end is journaled in a supporting standard 60. Adjacent the standard 60 the shaft 58 is provided with a spur gear 61 which is driven by a spur pinion 62 on a shaft 63 that is ournaled at its ends in one of the engine frames and in the standard 59. A worm-wheel 64 on the shaft 68 adjacent the spur pinion 62, is engaged and driven by a worm 65 on a shaft66 arranged at right angles to the shaft 63. The shaft 66 is journaled at its rear end in the standard 60 and extends forwardly therefrom toward the engine shaft l1. At its forward end, it is j ournaled on an upright 67. A pair of beveled gears 68 con nect the shaft 66 to a short shaft 69 that is journaled on an upright 69'. A spur gear 70 on the shaft 69 meshes with a larger spur gear 71 on the engine shaft 11. By the gearing described, the shaft 58v and the actuator cams 57 and 5'7 are slowly rotated in one or the other direction as the engine shaft 11 and drum 10 are rotated in opposite directions to raise and lower the cages connected to the drum. While the speed of the shaft 58 and the cams 57 and 57 thereon is directly proportional to the speed of the engine shaft, the reducing gearing between the engine shaft and the shaft 58 is such that the actuator cams will be very slowly ro tated. Indeed this gearing should be such that the actuator cams will not be rotated to more than one revolution while cars or cages are traveling from the top to the bottom of the mine shaft.

The rotary actuator cams 5'7 and 57 are arranged to effect the operation of the controlling shifters for the throttle valves and for this purpose are provided with segmental cam lugs 72 and 7%, each of which has an inclined cam face 73 at one end of an outer concentric face 74. The concentric face is preferably of considerable length. In the form shown it extends through an arc of about 90 degrees. The shifters operated by the actuator cams are in the form of arms or levers 75 and 75 that are provided on their ends with rollers 76 with which the actuator cams 57 and 57 engage. The shifter arms or levers 75 and 75 are pivoted intermediate their ends upon studs 77 that are carried by a pair of shiftable supports 78 and 78*. These supports are both pivotally mounted ona short stud shaft 79 at the lower front portion of the standard 59. The shiftable support 78 is provided at its upper end with an upwardly projecting lug or portion 80 and the support 78 is provided with a forwardly, projecting portion or lug 81, and these lugs are connected respectively by two links 82 and 83 to a pair of oppositely projecting crankarms 84 and 85 on the rock-shaft 36 of the reversing gear. The lower end of the shifter arm or lever 75 and the upper end of the shifter arm or lever 75 are connected by a pair of links 86 to a pair of crank-arms 87 on the rock-shaft 52 that is connected to the throttle valves. The free end of the shifter arm or lever 75 extends upwardly from its pivot and is arranged to be operated by the actuator cams 57 when the latter are rotated in the direction of the arrow shown in Fig. 3 to close the throttle valves. The free end of the shifter arm 75 extends downwardly from its pivot and is arranged to be operated by the actuator cam 57 to close the throttles when the actuator cams are driven in the reverse direction. The gearing between the drum or engine shaft 11 and the actuator cams 57 and 57 is so timed that one shifter arm will be operated to close the throttle valves when the cars or cages connected to the drum approach one end of their movement and the other shifter arm or lever will be operated to close the throttles when the cars or cages approach the opposite end of their movement.

With the parts in the position shown'in the drawings, the reverse gear of the engine is so set that the hoisting drum l0 and the actuator cams 57 and 57 will be rotated in the direction indicated by the arrows in Figs. 2 and 8. The throttle valve operating mechanism is shown in position in which the valves are open. As stated, two cars or cages will usually be connected to the drum by cables Wound upon the drum in opposite directions so that as the drum is driven one of the cars or cages will be raised and the other lowered. In the position shown, the shifter arm or lever 75 is in operative relation with the actuator cam 57, while the shifter-arm 75 is out of operative relation with the cam 57 a and would not be actuated thereby. As the car which is being raised approaches the surface, the inclined cam surface 73 of the lug 72 on the actuator cam 57 will engage the roller 76 on the shift lever 75 and throw it outwardly away from the axis of the cam so that the rock-shaft 52 will be rocked through the medium of the connecting link 86 and rock-arm 87 in the direction of the arrow indicated in Fig. 3 to close the throt tle valves. The concentric face 74 of the cam lug 72 will then hold the shifter arm 75 in its shifted position and will hold the throttle valves closed until the engineer first operates the reverse mechanism to effect the movement of the hoisting engine and drum in the opposite direction. To effect the re verse, he will shift the reverse lever 40 in the direction of the arrow indicated in Fig. 3 and thus rock the shaft 36 to move the valve of the auxiliary reverse engine. This movement of the shaft 36 in the direction ofthe arrow will move the supports 78 and 75 in opposite directions through the medium of the oppositely arranged crank-arms 84: and 85 and the connecting links 82 and 83 so as to throw the shifter arm or lever 7 5 away from its actuator cam 57 and the shifter arm or lever 75 into engagement with its actuator cam 57*. This will of course release the shifter arm 7 5 so that it may be moved and the throttle valves opened to drive the engine in the reverse direction. At the end of the movement of the engine in the reverse direction, the actuator cam 57 will engage the shifter arm '75 to close the throttles and the latter cannot again be opened until the engine is reversed to throw the shifter arm 7 5 away from its actuator cam and the shifter arm 75 back into operative relation with its actuator cam, 71. 6., into the position shown in the drawings.

It should be noted that each shifter arm has two independent movements one with the throttle valve controlling mechanism and one with the reverse gear. Vhen the throttle valves are closed both of the shifter arms will be out of operative relation with their actuator cams, but when the throttles are open one of the shifter arms will be in operative relation and the other out of operative relation with its actuator cam and, as the engine approaches the end of its move ment, the shifter arm in operative relation will be actuated to effect the automatic closing of the throttles. The shift of the reverse gear will of course throw one of the shifter arms out of operative relation and the other into operative relation with its respective actuator cam. The extended segmental surfaces 74 of the actuating cam will prevent the engineer from throwing the reverse mechanism to release the automatic throttling devices and then throwing the reverse gear back again to continue the movement of the engine in the same direction, since on the return of the reverse gear, one or the other of the shifter arms will engage one or the other concentric surfaces 74 on the cam lugs and will close the throttles.

The throttling mechanism is designed to be thrown into operation when one of the cars or cages is within a predetermined distance of the top of the mine shaft and the other has reached a point at the same predetermined distance from the bottom of the mine shaft so that the remainder of the movement of the cars is effected by the momentum of the moving parts. As stated, the engineer can only release the automatic throttling mechanism by reversing the engine to move the cars or cages in theopposite direction. Should the momentum of the moving parts be insufficient to complete the travel of the cars or cages in the direction in which they are moving when the throttles were closed, by-passes may be provided around the throttle valves so that a small amount of steam could be admitted to the engine cylinders to complete the travel of the cars. The mechanism, however, absolutely prevents through carelessness or inattention, from running the cars or cages to the extreme ends of their movement under a full head of steam so that accidents due to such overrunning are prevented.

It is obvious that numerous changes may be made in the details of structure set forth without departure from the essentials of the invention.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a. hoisting engine, the combination with means for cutting off the flow of motive fluid to the engine, of a shifter controlling the operation of said means, bodily stationary, rotatable actuator arranged to effect the operation of said shifter at a predetermined point, driving connec the engineer,

tions between the engine and said actuator and-engine reverse gear arranged to throw said shifter into and out of operative relation with said actuator.

2. In a hoisting engine, the combination with means for cutting off the flow of motive fluid to the engine, of a shifter controlling the operation of said means, a bodily stationary, rotatable actuator cam for effecting the operation of said shifter at a predetermined point, worm gearing connecting said actuator cam and the engine shaft, and engine reverse gear connected to said shifter to throw the same into and out of operative relation with Said actuator cam.

3. In a hoisting engine, the combination with throttling mechanism for the engine, of an operating shifter connected to said throttling mechanism, a bodily stationary, rotatable actuator cam'geared to and driven by the engine for operating said shifter at a predetermined point, a shiftable support whereon said shifter is'movably mounted,

and engine reverse gear connected to said support to throw said shifter into and out of operative relation with said actuator cam.

at. In a hoisting engine, the combination with a throttle valve, of an operating shift lever connected to said throttle valve, a bodily stationary, rotatable actuator cam for operating said shift lever at a predetermined point, worm gearing connecting said actuator cam and the engine shaft, a supportwhereon said shift lever is pivoted, said support being pivoted to swing at right angles to the axis of said cam to throw said shift lever into and out of operative relation therewith and engine reverse gear operatively connected to said support.

5. In a hoisting engine, the combination with means for cutting off the flow of motive fluid to the engine, of a pair of shifters controlling the operation of said means, a bodily stationary, rotatable actuator arranged to effect the operation of said shifters at predetermined points, driving connections between the engine and said actuator and engine reverse gear arranged to alternately throw said shifter into and out of operative relation with said actuator.

6. In a hoisting engine, the combination with means for cutting off the flow of motive fluid to the engine, of a pair of shifters controlling the operation of said means, a bodily stationary, rotatable actuator geared to the engine shaft and driven in opposite directions thereby and arranged to effect the operation ofsaid shifters at predetermined points, and engine reverse gear operatively connected to said shifters and arranged to alternately throw the same into and out of operative relation with said actuator.

v7. In a reversible hoisting engine, the combination with throttling mechanism for the engine, of a pair of shifters for controlling the operation of said throttling mechanism, a pair of bodily stationary, rotatable actuator cams geared to the engine shaft and each driven in opposite directions thereby, supports whereon said shifters are movably mounted, said support being movable to and from the axes of said actuator cams, and engine reverse gear connected to said supports to alternately throw said shifters into and out of operative relation with said actuator cams.

8. In a hoisting engine, the combination with throttling mechanism for the engine, of apair of shifters controlling the operation of said throttling mechanism, a pair of shiftable supports whereon said shifters are movably mounted, a pair of bodily stationary, rotatable actuator cams for operating said shifters at predetermined points, reducing gearing connecting said cams and the engine shaft, engine reverse gear, including a rock shaft, oppositely disposed arms on said rock shaft and connections between said arms and said supports for alternately throwing said shifters into and out of operative relation with said actuator cams.

9. In a reversible hoisting engine, the combination with throttling mechanism for the engine, of a shifter automatically controlling the operation of said throttling mechanism, a bodily stationary and rotary cam for operating said shifter at a predetermined point, a gear rigidly connected to said cam, a counter-shaft having a gear meshing with said cam gear, worm gearing connected to and driven by the engine for driving said counter-shaft, and means for setting said shifter into and out of operative condition.

10. In a hoisting engine, the combination with the engine shaft and throttling mechanism for the engine, of a shifter controlling the automatic operation of said throttling mechanism, a bodily stationary rotary cam for actuating said shifter at a predetermined point, a shaft whereon said cam is fixed, a gear fixed to said. shaft, a countershaft having a gear meshing with said cam gear, a second counter-shaft connected to and driven by said engine, worm gearing connecting said counter-shafts and means for throwing said shifter and said cam into and out of operative relation.

11. In a hoisting engine, the combination with the engine shaft and a throttle valve for the engine, of a hand-lever and a shift-er connected to said throttle valve, a bodily stationary rotary cam for automatically operating said shifter at a predetermined. point, a shaft whereon said cam is fixed, agear fixed to said shaft, a countershaft parallel with said cam shaft and having a gear meshing with said cam gear, a second counter-shaft at right angles to said first counter-shaft and connected to and driven by the engine shaft, worm gearing connecting said counter shafts, and means for setting said shifter into and out of operative condition.

12. In a hoisting engine, the combination with the engine shaft, and a throttle valve for the engine, of a rock-shaft connected to said throttle valve, a hand-lever and an automatic shifting lever connected to said rock-shaft, a bodily stationary rotary cam for actuating said shifting lever at a predetermined point, a gear fixed to said cam, a counter-shaft parallel with the shaft of said cam and having a gear meshed with said cam gear, a second counter-shaft arranged at right angles to said first countershaft and connected to and driven by the engine, worm gearing connecting said counter-shafts, and means for throwing said shifter and said cam into and out of operative relation.

13. In a hoisting engine, the combination with the engine shaft and throttling mechanism for the engine, of a pair of shifters controllingthe automatic operation of said throttling mechanism, a pair of bodily stationary rotary actuator cams for operating said shifters at predetermined points, a gear rigidly connected to said actuator cams, a countenshaft having a gear meshing with said cam gear, worm gearing connected to and driven by the engine shift for driving said counter-shaft, and means for alter nately setting said shifters into and out of operative condition.

14c. In a hoisting engine, the combination with throttling mechanism for the engine, of a shifter controlling the automatic operation of said throttling mechanism, a bodily stationary rotary cam arranged to effect the operation. of said shifter at a predetermined point, a gear rigidly connected to said cam, reducing drive gearing interposed between said gear and the engine shaft, engine reverse gear and means operated by said engine reverse gear for throwing said actuator cam and shifter into and out of operative relation.

15. In a hoisting engine, the combination with the engine shaft and throttle valve for the engine, of a shift lever connected to said throttle valve, a bodily stationary rotary cam for actuating said shift lever, a shaft whereon said cam is fixed, a gear fixed to said shaft, a counter-shaft having a gear meshing with said cam gear, worm gearing connected to and driven by the engine shaft for driving said counter-shaft, engine reverse gear, and means connected to and operated by said engine reverse gear for throwing said actuator cam and said shifter into and out of operative relation.

16. In a hoisting engine, the combination with throttling mechanism for the engine, of a shifting member connected to said throttling mechanism, a rotary cam member arranged to effect the operation of said shifting member at a predetermined point, driving connections between the engine and said cam member, a support movable at right angles to the axis of said cammember whereon one of said members is mounted and engine reverse gear connected to shift said support to throw said cam and said shifting members into and out of operative relation.

17. In a hoisting engine, the combination with throttling mechanism therefor, of a pair of shifting members connected to said throttling mechanism, a pair of rotary cam members arranged to effect the operation of said shifting members at predetermined points, gearing connecting said cam members and the engine, a pair of supports whereon one pair of said members are mounted, said supports being shiftable at right angles to the axis of said rotary cam members, and engine reverse gear connected to said supports to shift the same in opposite directions and to alternately throw said cam and shifting members into and out of operative relation.

18. In a hoisting engine, the combination with throttling mechanism therefor, of a shifter controlling the automatic operation of said throttling mechanism, an actuator cam connected to and driven in opposite directions by the engine arranged to effect the operation of said shifter at a predetermined point, a shiftable support whereon said shifter is mounted, said shifter being movable independently of said support to effect the operation of said throttling mechanism, and engine reverse gear connected to said support to throw said shifter into and out of operative relation with its actuator cam.

19. In a hoisting engine, the combination with throttling mechanism therefor, of a shifter controlling the automatic operation of said throttling mechanism, a rotary actuator camv connected to and driven in opposite directions by the engine for operating said shifter at a predetermined point, a support whereon said shifter is mounted, said support being movable at right angles to the axis of said cam to throw said shifter into and out of operative relation therewith,

and engine reverse gear connected to shift said support.

20. In a reversible hoisting engine, the combination with throttling mechanism for the engine, of a pair of shifters controlling the automatic operation of said throttling mechanism, a pair of rotary actuator cams connected to the engine, each driven in opposite directions thereby and arranged to effect the operation of said shifters at predetermined points, a pair of supports whereon said shifters are mounted, and engine reverse gear connected to said supports and arranged toalternately shift the samein opposite directions to throw one of said shifters into operative relation with its actuator cam and the other out of operative relation with its actuator cam.

21. In a hoisting engine, the combination withthrottling mechanism for the engine, of a pair of shifters connected to said throttling mechanism, a pair of rotary actuator cams connected to and driven by the engine for operating said shifters at predetermined points, a pair of movable supports whereon said shifters are movably mounted, engine reverse gear including a rock-shaft, and oppositely arranged arms on said rock-shaft connected to said supports to shift the same in opposite directions and throw one of said shifters'intooperative relationwvith its actuator cam and the other out of operative relation with its actuator cam.

22. In a reversible hoisting engine, the combination with a throttle valve for the engine, of a pair of shift levers connected to said throttle valve, a pair ofrotary actuator cams connected to the' engine and each driven in opposite directions thereby for operating said shift levers at predetermined points, a pair of supports whereon said shift levers are pivotally mounted, said supports being movable to throw said shift levers into and out of operative relation with the corresponding actuatortcams, and engine reverse gear connected to said supports to throw one of said shift levers into operative relation and the other out of operative relation with its actuator cam.

23. In a reversible hoisting engine, the combination with a throttle valve for the engine,of-a pair of shift levers connected to saidthrottle valve, a pair of rotary actuator cams connected to the engine and each driven in opposite directions thereby for operating said shift levers at predetermined points, a pair of pivoted supports whereon copies ofthis patentmay'be obtained'for five cents each, by addressing the sa-idshift levers are pivoted, said supports being movable to and from said actuator cams to throw said shift levers into and out of operative relation therewith, engine reverse gear including a rock-shaft, and oppositely arranged arms on said rock-shaft connected to said pivoted supports.

24- In a hoisting engine, the combination with the engine shaft and throttle valve for the engine, of a rock-shaft connected to said throttle valve, a hand-lever connected to said rock-shaft, a pair of shift levers connected to said rockshaft, a pair of rotary actuator cams for operating said shift levers at predetermined points, worm gearing connecting said actuator cams to the engine shaft, a pair of pivoted supports whereon said shift levers are mounted, engine reverse gear including a rock-shaft, a hand-lever connected to said reversing rock-shaft, a pair of oppositely arranged arms on said reversing rock-shaft, and links connecting said arms to said shift levers.

25. In a hoisting engine, the combination with throttling mechanism therefor, of a pair of shifter members controlling the au tomatic operation of said throttling mechanism, a pair of rotary cam members held against axial movement for actuating said shifter members at predetermined points, gearing for driving said actuating cam members in opposite directions, a pair of supports Whereon one pair of said members are mounted, said supports being shiftablo at right angles to the axis of said rotary cam members, an engine reverse gear connected to said supports to shift the same in opposite directions and alternately throw said cam and shifting members into and out of operative relation.

SVEN T. NELSON. Witnesses HARRY L. CLArP, CLARA A. NORTQN.

Commissioner of Patents.

Washington, D. G. 

